1. Field of the Invention
The present invention relates to a liquid starch composition, especially to a uniform transparent aqueous liquid starch composition. The solid components of the composition consist essentially of three specifically combined components, that is, a nonionic surfactant having one or more polyoxyethylene radicals in the molecule as a hydrophilic group, a nonionic water soluble polymer having hydroxyl radicals or pyrollidone radicals, and a fluorescent optical brightener which is a 4,4'-bis(2-sulfostyryl)biphenyl salt.
2. Description of the Prior Art
It is well known that the whiteness of clothes made of hydrophilic fibers, such as cotton, which has changed to a yellowish or grayish color while being used, can be recovered by washing, bleaching or treating with fluorescent optical brighteners available at home. On the other hand, the recovery of whiteness of clothes made of hydrophobic fibers, such as polyester fibers, is generally difficult, and almost impossible by means available at home.
Starch compositions used by housewives for finishing clothes are categorized into aerosol spray starch compositions or aqueous liquid starch compositions. The aerosol spray starch composition consists of a gaseous propellant phase, a liquified propellant phase and an aqueous phase to be sprayed. Such compositions are disclosed in U.S. Pat. No. 3,547,854 to W. Ruth et al. and in U.S. Pat. No. 4,023,978 to R. P. Messina.
The main component of the aqueous liquid starch composition is a water soluble or dispersible polymer, such as alpha-starch, modified starch, polyvinyl alcohol or polyvinyl acetate. Many kinds of additives to improve the composition are known. For example, in Japan Patent Publication No. 1967-9517, a propylene oxide and ethylene oxide adduct of a higher aliphatic alcohol is added to an aqueous starch composition for the purpose of improving lubricity on ironing. In U.S. Pat. No. 3,066,036 to Cortin et. al., a liquid starch composition comprising an oxidized starch, a polyethylene glycol ester of a fatty acid, boric acid and borax is disclosed. In U.S. Pat. No. 3,419,405 to Lang, a starch composition comprising a pre-gelatinized starch and a laundry souring agent, stability of which is improved by adding an anionic or nonionic surfactant, is disclosed. In U.S. Pat. No. 3,708,466 to Kappler, an aqueous size composition comprising (1) an unmodified starch, (2) polyvinyl acetate emulsion, (3) an anionic or nonionic surfactant and (4) laundry sour is disclosed.
It is also known that some commercial liquid starch compositions for clothes contain fluorescent optical brighteners and as their main component a water soluble or dispersible polymer. Such starch compositions not only make clothes rigid but also contribute to the whiteness recovery of clothes. A triazinylaminostilbene type fluorescent optical brightener is one of the most conventional types used in liquid starch compositions.
An aqueous dispersion of a fluorescent optical brightener, stabilized by adding (a) a water soluble salt and (b) a nonionic water soluble polymer or a nonionic surfactant is disclosed in Japan Patent Publication (laid open for public inspection) No. 1976-111238. In this publication, a sufficient amount of the water soluble salt is contained in the dispersion to inhibit the dissolution of the fluorescent optical brightener.